Some common vitamin deficiency symptoms include hair loss, brittle nails, dry skin, acne, eczema, low energy, low moods, and fatigue. In particular, pregnant or nursing women, and vegan or vegetarians are more susceptible to vitamin deficiency. For example, some of my clients who are vegans and vegetarians, come in to see me because they are experiencing low energy, chronic fatigue, skin, and hair issues. Part of this is because some of them are what we consider ""junk food"" vegetarians, meaning they eat mostly processed, refined foods, so they're not getting enough fresh, whole foods which have most of the real vitamins. Because of a lack of essential vitamins, nutrients, and minerals, they start experiencing the deficiency symptoms I mentioned. So it's really important to make sure, especially if you're pregnant, nursing, vegan, or vegetarian, that you're getting enough of the right kinds of foods, and that includes an abundance of fruits and vegetables, whole grains and high quality proteins. If you're still having trouble or for some reason are unable to get the kinds of food you need, then you may consider taking a supplement. For example, a vegetarian or vegan who doesn't eat any animal products may be deficient in vitamin B-12, so they may wanna consider adding a B-12 supplement to what they're eating. And also it's really important for pregnant and nursing mothers to take a prenatal multivitamin so they can get the added vitamins and nutrients they need and not experience vitamin deficiency. They, in particular, need extra calcium, iron and folic acid to ensure a healthy pregnancy.